function s1_generate_a_series_of_files(){
    for i in {1..100};do 
        echo -n $i > /tmp/new_file$i;
    done
}

function s2_list_4_files_in_long_format_about_account_and_group(){
    ls -l /etc/{passwd,shadow,group,gshadow} | sort 
}

function s3_find_items_related_to_given_username(){
    grep -E  "^$1:" /etc/{passwd,shadow} | cut -d: -f1-7 | sort 
}

function s4_find_items_related_to_given_group_name(){
    grep -wE "^ $1:" /etc/{group,gshadow} | cut -d: -f1-4 | sort 
}

function s5_create_groups_for_given_group_names(){
    groupadd rnd && groupadd itoperation
}

function s6_create_users_and_set_their_group_as_required(){
    useradd -G rnd adam && useradd -G rnd bob && useradd -G itoperation calvin && useradd -G itoperation david && useradd -G rnd edward
}

function s7_change_users_shell(){
    usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}

function s8_set_password_change_policy(){
    chage -M 60 -m 10 -W 10 adam
    chage -M 60 -m 10 -W 10 bob
    chage -M 60 -m 10 -W 10 david
    chage -M 60 -m 10 -W 10 calvin
    chage -M 60 -m 10 -W 10 edward
}

function s9_set_password_for_five_users(){
    usernames=("adam" "bob" "calvin" "david" "edward")
    for username in "${usernames[@]}";do
        passwd -l "$username"
    done
}

function s10_lock_bobs_password(){
    passwd -l bob
}

function s11_include_adam_into_wheel_group(){
    if grep -q '^wheel:' /etc/group;then
        usermod -aG wheel adam
    else
        groupadd wheel
        usermod -aG wheel adam
    fi
}

function s12_change_files_permission(){
    for i in $(seq 3 3 99);do
        chmod 640 /tmp/new_file$i
    done
}

